Control system for a compacting machine

ABSTRACT

A control system for a compacting machine is provided which includes a compaction chamber into which material to be compacted is placed, a pressure plate spanning the area of the chamber for compressing the material, and a reversible drive source for moving the pressure plate in forward and reverse directions within the chamber. The control system selectively enables driving of the pressure plate to effect performance of baling, packing and return cycles of the machine and provides output indications of the operating condition of the machine, the direction of movement of the pressure plate, and the full condition of the compaction chamber. A time delay circuit automatically shuts down the machine when any of the operational cycles continues beyond a predetermined time limit.

Potter [54] CONTROL SYSTEM FOR A coMPAcnNG MACHINE Richard W. Potter,Downers Grove, Ill.

Assignee: McGraw Edison Company; Elgin;

Ill.

Filed: Aug. 21, 1972 Appl. N O.Z 282,413

[75] I lnventori [52] US. Cl...'. 100/52, 100/3, 100/53,

w ns]; Dec. 24, 1974 FOREIGN PATENTS OR APPLICATIONS 321,570 1111929GreatBritain ..l00/256 Primary Examiner-Billy J. Wilhite Attorney,Agent, or Firm-John L. Parker [57 ABSTRACT A control system for. acom'pacting machine is provided which includes a compaction chamber intowhich material to be compactedis placed, a pressure I fplate spanningthe area of thechamber for compress- 100/99, 100/215, 100/218, IOU/269R, 200/6162 ing'the material, and a reversible drive source 'for [51]Int. Cl B30 b-f15/1'6 moving the pressurejfplate in forward and reversedi- [58] Field of Search..'..... ZOO/61.62; 335/205; e s it vthe ch mThe nt o y te e ec- 100/52, 50, 53, 99,256, 3, 8,- 215, 218, 269 tivelyenables driving of the pressure plate to effect a I l R Y performa nceof baling, packing and return cycles of the machine and provides outputindications of the [56] References Cited operating condition of themachine; the direction of UNITED STATES PATENTS movement of the pressureplate, and the full condition 3 229 618 H1966 (305mm 6 5 of thecompaction chamber. time delay circuit auto- 2 3,353,478 1 m Hopkinsloo/52 matically shuts down the machine when any of the op- 3:539:74l11/1970 Volandf: erational cycles continues beyond a predetermined 73,606,830 9/1971 Chaney... 100/5'2 limlt- 3,627,959 l2/l97l Chapell..;200/6L62 3,762,312 1011973 Guhl.. 100152 a 4 C GYDraWmg Fgures Pmmmnscwmw www w CONTROL SYSTEM FOR A COMPACTING MACHINE DESCRIPTION OF THEINVENTION popular for reducing the volume of paper waste and otheruseful but bulky commodities, as well as for the crushing of refuse inboth home and commercial environments. The rapdily expanding usage ofsuch machines has compounded the-incidenceof injury resulting from theinherent dangers attendant, tothe operation of the power-assistedcompaction process. Conventional compaction machines have employedfew,if any, safety'features'beyond the usual safety interlock on thedoor tothe compaction chamber.

It is a general object of the present invention to provide a control fora compacting machine which provides a degree .of safety to the operatorwhich has heretofore been unavailable in such machines. Morespecifically, it is an object of the present invention to provide acontrol system for a compaction machine which includes a non-defeatabledoor interlock and which provides for theoperator visual indicationsofthe operating condition of the machine so as to minimize the possibilityof injury resulting from, operator mistake in using the machine.

lt is a more specific object of the present invention to provide acontrol system for a compacting machine whi'chgivesvisual indications ofthe operating or ON condition of the machine, the direction of movementof the pressure plate andthe full condition of the compaction chamber. tv

- 'Yet'another object of the present invention is to provide a controlsystem'which protects the operator and i v the machine in the event oflamalfunction which causes any operational cycle of the ma'chine'tocontinue for an I excessively long time period. A related object of theinvention is-to provide forautomatically shutting down the machinewhen-any of the operational cycles continu'es byond a normal timeperiod.

Prior compaction machines have also been devised for operation in abaling mode, in which the'contents of the compaction chamber are held ina compressed state for manual binding by the operator. However, the

known machines useful for this purpose have required that the operatorcontinually monitor the operation of the pressure plate and manually,shut down the machine at or near the point of maximum compactionpressure.

provide a control system which senses the condition of maximumcompaction pressure during the baling operation and automatically holdsthe compaction chamber. contents in a compressed maximum-pressure stateso as tofacilitate baling A still further object of thepresent inventionis the provision of a control system which provides repetitive tampingof the chamber contents during each operational cycle of the machineas-the chamber volume reverse directions'through the compaction chamberreaches the full level, thus creating a tightly compacted bundle. Otherobjects and advantages of the present invention will become apparentupon reading the following detailed description and upon reference to.thedrawings, in which: I

FIG. 1 is an elevational view of a compaction machine embodyinga'contr'ol system constructed in accordance with the present invention;v FIGS. 2a -2 c, when taken together, constitute a schematic diagram ofthe electrical circuit used in the control system of the presentinvention. v

FIGS. 3a-3b are exploded detail views. of a limit switch-arrangement. ti

While the invention will be described in connection with preferredembodiment, it willbe understood that placed in the lower section of thecompaction compartment 12 for receiving the material to be compacted,removal of the box 20 being facilitated by an ejection strap 22 whichgenerally lies behind and under (from the operators standpoint) the box20. At the lower end of the ejection strap 22 is a handle-24 throughwhich the operators hand may be inserted during ejection of the.box 20.'At a point above the level of the box 20 there is provided'in the doorI6' an'a pertur e '26 normally covered by a hinged door 28 which, whenopened, forms-a chute through the door 16 into the box 1 During normalserviceas a'compacting machine, the material to be compacted isinserted into the'closed chamber 12 through the chute formed in theaperture 26 of the door 16. For compressing the contents of the chamber'12 a pressure plate 30 is provided which of such a size as tosubstantially span the horizontal area of the chamber 12 and, inparticular, the horizontal area of the box 20. The plate 30 is guided bya pair of vertically extending guide bars 32, 34 extending upward intothe control chamber 14.

For moving the pressure plate 30 in the forward and 12, there isprovided a' reversible drive souce in the form of a motor and hydraulicpump, indicated generally at 40, which positions a hydraulic ram 42which n runs downward through the machine into engagement at itslowerend with the pressure plate 30. Areservoir 46 provides hydraulic fluidfor the motor 40.

Although many different drive sources could be employed with the presentinvention, a particularly suit- I able drive source, and theoneenvisioned in the following description, includes a two-stage doublepump having a solenoid-controlleddirectional valve which'is ac-' tuableto change the directionof motor force on the hydraulic ram 42. The pumpis driven by an electrical motor selectively controlled by an electrical.relay in a ,manner hereinafter described. Also housed inthe chamber 14is a control circuit module 50 having a of indicators and sides of thepower line have switches 62, 64 connected in series therewith andcontrolled manually by a front panel key-locked actuator 66. The motor68 of the hydraulic motor and pump unit 40 is selectively connectedacross the switched side of the 120 volt line by a normally openedcontact set 70 of the drive motor relay 72. Similarly, a drive solenoid74 for the directional valve of the motor and pump unit 40 is connectedin series across the switched 120 volt line through a pair of normallyopened contacts 76 of the directional hydraulic valve relay 78.

control circuit of the dc. operating power whenever the doors 16,28tothe cabinet'are open. To this end, a magnetically actuated switch130 is provided in series vwith the dc. supply output 114 and theoperate lamp a For converting the a.'c. electrical inputpower into aplurality of do. electrical voltages for usein the control circuit,there is provided a power supply module, indicatedgenerally at 80,including a principal supply transformer 82 having a primary winding 84one half of which is connected in series with. the switched supply linesthrough a protection fuse 86. A neon lamp 88 in series with a currentlimiting resistor 89 is also connected across the same half of theprimary winding 84 to provide a visual indication of the presence of 120volt a.c. input voltage to the power supply-module 80, and is located onthe power supply module 80. A secondary winding 90 of the split type iscenter tapped to provide a ground line 92 and, operating in conjunctionwith a pair of rectifier diodes.94, 96 forms part of aconventionalfull-wave rectifier commonly used in the power supply art.The outputfrom the rectifier is applied across a smoothing capacitor 98which, to a large degree, removes the ripple from the rectified signaland 7 provides a first dc. voltage on asupply output line 110 which isapplied to one side of both the motor drive relay 72 and the directionalhydraulic vavle relay 78. The output line 110 also provides power forthe pressure plate direction indicator lights 246, 300and the fullcondition lamp 440 in a manner hereinafter described.

A sec ondand lower d.cl supply. voltage is provided on an output line114, which is connected to the power line 110 through a droppingresistor 116 and is further regulated by a smoothing network consistingof a capacitor 118 and resistors 119, 120. The dc. supply line 114provides a low level d.c. signal, typically -l2 volts, for thesmall-signal switching circuits hereinafter described. 7

In accordance with one aspect of the present inven- 126, the seriescircuit further including an operatind diode 132 between the magneticswitch 130 and the lamp 126. A permanent magnet 134 is installed in thechute door 28 (FIG.- 1) and is operative to close the contact of theswitch 130 whenever the doors 16, 28

,are both closed at the'same time so as to. bring the magnet 134 intoproximity with a detecting pickup 136 located on the side panel 10. Anindication of the closed condition of the two doors 16, 28 is providedby the lamp 126, which is illuminated to a high brilliance by currentflowing through themagne-tic switch 130 and diode 132 from the dc.supply line 114.

The control system of the present invention can be broadly characterizedin terms of its principal modes of operation, which .are briefly setforth here and described in detail ina later section of thespecification.

First, one of the principal modes of operation is the compaction or PACKfunction, in which the pressure plate 30 moves from its uppermostorRETURN position down through the chamber 12 to compact the materialpreviously inserted therein, followed by the automatic return of thepressure plate 30 to its uppermost position. To this end, the controlsystem provides means responsive to a packing initiationsignaland-operatively associatedwith the reversible drive source toadditional means respond to this output signal from thesensing means toreverse thedirection of operation of tion, an output indication isprovided whenever the main key-operated power switch 66 is actuated. Tothis end, a third output from the power supply module 80 is provided onan output line 122, which is connected to the output'line 114 through adropping resistor 124. An indicator light 126 is provided on'thejfrontpanel of the module and is connected to the output 122. Sufficientcurrent is drawn through the dropping resistor 124 to actuate the light126 to a low but visible level of illumination indicating that theoperating switch. 66 is on but that at least one of the doors 16, 28 tothe cabinet is not'closed.

A related featureof the invention lies in the provision .of a magneticinterlock switch which cannot be defeated by normal techniques and whichdeprives the the drive source so as to retractthe pressure plate 30.Finally, position responsive means renders the drive source inoperativeon the achievement of the fully retracted position'of the pressure plate30. v

It is usually unnecessary for the top panel ll of the compaction chamber12 to beresisfiiift fihecompaction pressure normallyattained in thechambe'r l2inasmuch as these pressures are exerted downwardly on theside walls and bottom of the chamber by the pressure plate 30. For thisreason the top panel 11 of the compression chamber is usually formed ofrelatively lightwight material and is not adapted to withstand highpressures. Under these circumstances it is possible, however, that somerefuse being compressed, may inadvertently bypass the pressure plate 30during downward travel of the plate in the chamber, withj'the resultthat some suchmaterial ends up on top of the pressure plate. Anotherway'in which this could occur would be if the operator inadvertentlyadmitted refuse to be I compacted into the chamber 12 when the pressureplate 30 was in some position other than its uppermost position.

Forthe purpose of detecting the presence of any refuse being compactedon top of the pressure plate 30 soon enough to prevent damage to the toppanel 11 of the'chamber 12, a limitswitch arrangement 31 is provided, asshown in FIGS. 3a and 3b. The limitswitch arrangement. 31 includes avertically disposed rod 33 which is slidably mounted to the frame 35 ofthe compaction machine by means of a pair of vertically spaced pillowblocks 37 and 39. The lower end of the rod 33 is arranged to extenddownwardly. slightly into the compaction chamber 12 when the'pressureplate 30 is. not in its uppermost position (see- FlGp3b). when thepressure plate moveslupwardlyin thechamber 12 toward its uppermostposition, itapproaches and engages the lower end of the rod 33 andaccordingly forces the rod upwardly. Means in the form of, a collar 41provided near the upper end of the rod 33 is provided for terminatingupward movement of the-pressurelplate 30'when the plate is invitsuppermost position by tripping the switch 164 also mounted on the frame35 of the inachine (see also FlGrl Akeeper'collar 43-is also provided onthe rod 33 to hold the rod in place during repair if necessary, andother collar 45 mounted near the lower end of the rod 33 limits thedownward movement of the rod into the compression chamber 12 byengagernent with the top panel 11; The rod 33 is biased by means of acoil spring 47Idisposed between ,the 'upper spring normally urging therod downwardly so that the lower collar 45 is disposed, against the toppanel 11 of the compaction chamber l2.

Thus it is seenthat the'pres'sure plate 30 moves upwardly within thechamber 1 2, if any refuse is inadvertently present in the'space betweenthe pressure'plate and the top panel 11 of the compaction chamber, the

limit switch arrangement .31 will function to terminate upward movementof the pressure plate (via the collar 41 and switch-l64);beforecompaction of the refuse serted. lf,:however, after the secondcompaction the volume remains above the full leveLthe operator issignaled with a visual indicating light that the chamber 12 is full,indicating'that thel'contents should be removed before furthercompacting isattempted To this end, the apparatus described abovefurtherincludes a volume sensing'deviceproviding an in'dicatiohflthatthevalue. The output signal generatedin response tothis maximum pressurecondition acts'u'pon means associated with the drive source to stop-theforward advancement of the pressure plate 30 and hold the contents ofthe chamber 12 at the predetermined threshold pressure. Finally, meansare provided for reversing the operation of the' drive source inresponse to a inanual initiation by the operator so as to. retract thepressure plate 30 and allow removal of the compressed contents.

Various other features of the presentinvention, such .as the automaticshut-off safety feature, will become apparent from'the followingdetailed description of the circuits of FIGS. 2a-2c. t

' Returning then to FIG. 20, there is-showna manual mode selector switch140 of the momentary contact type with contacts 142 through 146 andspring biased to acentral OFF -position. The contact 14l'is electri- 1cally connected directly to the outputline 114 from the pillow block37-a'nd the switch'actuating collar 41, the

compressed volume is less than a predetermined threshold volume and atime delay device associated with the aforementioned pressure and volumesensing devices and operative to begin a timed period when ever theoutput signal from the pressure sensing device occurs before thecompressed volume falls below the predetermined threshold volume.Finally, there is proto reverse the direction of thedrivesource so as tocause a second compression of the contents of the chamber 12:.After'this occurs additional means are provided for illuminating thefull condition indicator lamp 440. if, a second compression havingoccurred, the output signal from the pressure sensing means again occursbefore the compressed volume hasfallen below the predetermined thresholdvolume.

Third, the control system ofthe present invention provides an automatic'balingfunction. In the BALE mode, the pressure plate 30 responds to abaling initia-,

tion signal to advance through the chamber 12 until the pressure of thecontents of the chamber 12 against the vided means responsive to the endof the timed interval dic. supply 80, while the contacts 143,. areconnected torthe same outputline' 114 through the magnetic doorinterlock switch 130. The switch 140 is a threeposition switch having,inaddition to the OFF position. BALE and PACK-RETURN positions. Threeprincipal output terminals 148, 150,152- are controlled by the;switch140 and provide the primary function ini- 'tiating signals for thecontrol system. Specifically, during normal-operation the terminal 148:is high (apositive dc. voltage) whenever' the mode selector switch, 140is in the OFF or BALE positions and low whenever theswitch 140 is in thePACK-RETURN position, That is, the contacts 141', 1.42 are normallyclosed whenever switch 140 isin the OFF or BALE position and normallyopen .whenever switch 140 is .in the PAC K RETURN position. Theterminals 150, 152 are supplied by the dc. supply output line 114 whenthe mode selector switch 140 is respectively in the BALE and PACK RETURNpositions, assuming that the doors 1 6,

' 28,'and hence the magnetic switchl30,, are closed. I

That is, the;.contacts 143 through 146 are normally open. The contacts143, 144 are closed only when the switch 140 is in the BALE positionandthe contacts 145, 146 are closedonly when the switch 140 is in thePACK-RETURN position, At all other times, the terminals 150,'152 areelectrically isolated. As such, the 1 switch 140 mayv be manuallyengaged to providea packing initiation signal on the terminal 152 or -abaling initiation signal on the terminal 150.

For the purpose of sensing when the resistance pressure of the contentsof the chamber 12 against the pressure plate 30 reaches a predeterminedthreshold value,

there is provided a pressure sensingswitch of the single-poledouble-throw type having its common pole connected to the interlockedoutput of the power. supply 80 through a dropping resistor 162 and anormallyclosedswitch 164. The details of the pressure switch 160 arewithin the knowledge of those skilled in the art and need not be setforth here. Suffice it to say that the contact arm of the switch 160normally assumes the lower.(shown) position when the pressure is belowthreshold and is actuated to the upper position when the pressure isabove threshold. The switch 160'may be responsive to mechanical stresson the pressure plate 30 or chamber 12 forv instance. Preferably,however,

, the switch 160 is hydraulically actuated-and is responpressure plate30- reaches a predetermined threshold sive to the build-up of'pressurefluid behindthe hydraulic ram 42. In its-lower position, the switch 160'norother times.

mally provides a positive supply signal to aterminal 166 which controlsdriving down of the pressure plate or return position. Therefore, duringoperation of v the compaction unit, the switch 164 is closed to providea holding signal (the significance of which will become clear) at aterminal 170 and a dc. input signal to the pressure switch 160. p

A second pressure plate position sensing switch 172, hereinafter calledthe low limit switch, is connected in series with the normally opencontact of the pressure switch 160 and operates in conjunction with theswitch 160 to provide a positive dc. voltage of the terminal 174whenever the contents of the chamber 12 exceed a predetermined fulllevel at' the end of the downward motion of the pressure plate 30.Specifically, the switch 172- is closed whenever the-pressure plate 30is above the full .level and open when the plate 30 is below the fulllevel. Therefore, a full condition indicating signal is produced atterminal 174 only if the pressure plate 30 encounters the thresholdresistance pressure while at a position-above the low limit thresholdlevel.

Turning now to FlGS. 2b and 20, it is seen that'the terminals to theleft of these FlGS. correspond in numher to the terminals to the rightof FIG. 2a,- and for clar- 8. resistor 202 and a base-emitter biasnetwork consisting of resistors'204, 206. The junction of the'resistors204, 206 receives a drive signal from the cathode of the SCR 184. Thetransistor 200 is referenced to ground potential through the emitterresistor 202 and has its collecj tor connected to one terminal of themotor drive relay solenoid 72through the connecting terminal 208.

It should be notedat this point that the energization of the motor driverelay solenoid '72 (FIG. 2a) initiates movement of the pressure plate 30in one direction or the other, depending on the condition ofenergization of the directional valve solenoid 78. The directional 212consisting ofa transistor 2140f the NPN type'having its emitterreferenced toground through a resistor 216 and its base biased by anetwork consisting of resis-' .tors 218, 220. The collector of thetransistor 214 is connected to the control terminal of thedirectionalvalve solenoid 78 through a terminal connector 222.

' When rendered conductive, the. transistor 214 is operaity, areprovided with functional designations providing ease of description. Thereader is cautioned not to assume that all. signals necessarily flowfrom'left to right, since the reverse is often true, particularly in theinstance of the hold terminal 170 and the lower six terminalshereinafter described; I lt will be recalled that the initiation signalsprovided at't he terminals'l50, 152 for the BALE and PACK- RETURNfunctions are momentary. For the purpose of providing a memory duringthe respective BALE and PACK-RETURN operations, there is provided abalememory, circuit :180 anda pack memory circuit 182 I which aresimilar, butnot identicalin operation. The

bale memory circuit 180 assumes a first state during the entire balecycle and a second state at all other times. The pack memory 182 assumesa first state during the entire pack or return cycles and a second stateat all Taking the pack memory 182 first, it is seen that the circuit isprincipally composed of a silicon controlledrectifier (SCR) 184 havingits anode supplied by a hold line 171 connected to the hold terminal 170and its cathode terminal connected to, among other things, a motor relaydrive circuit 186. The gate terminal of the SCR- 184 receives itstrigger signal from the packinitiation signal at the terminal 152through an RC decoupling network 188, a blocking diode 190 and aresistor The motor relay driver circuit 186 includes a switchingtransistor 200 of the NPN type. an emitter dropping tive to energize thesolenoid 78. I

The down relay driver circuit 212 is initially rendered conductive byeither the bale initiate pulse at. terminal 150 or the pack initiatepulseat terminal 152. Specifcally, the bale initiate pulse reaches therelay drive through an R-C decoupling circuit 226, a directional diode228 poled to conduct current toward thetransistor 214 and a pair ofseries resistors230, 231, the latter of which supplies current to thejunction of the resistors 218, 220 to bias the transistor 214 intoconduction.

The pack initiation signal at the terminal '152 simi larlybeginsconductionin the driver transistor 2 14 by providingcurrent to thetransistor through.aidirectional diode 236 and the aforementionednetworkconsisting of the series resistors 230, 23l,and the bias networkconsisting of the resistors 218, 220.

connected to the bias resistors 218, 220 of .the directional solenoid'driver circuit 212 and its gate terminal connected to the junction ofthe bias resistors 230, 231, 394. Anode current for the SCR 242 isnormally provided from the power supply through the normally closed(lower position) terminal of the pressure switch 160, the drive-downterminalconnector 166 and an R-C decoupling network 244. i

While the relay driver circuit 212 is held in conduction by theconducting SCR 2420f the drive down 0 memory circuit 240, a visualindication of downwardtor lamp 246-on the front panel 50 (FIG. 1 andFIG. v

2a). As in the case of the down direction solenoid 78,

travel of'the pressure plate 30 .is provided by an indicasustainingcurrent for. the down direction indicating light 246 is primarilyprovided by the drive down memory circuit240. To this end, there isadditionally provided a down lamp driver circuit 250 which includes atransistor 2520f the NPN type having its emitter couthebale memorycircuit 180.

pled to ground through a resistor 254, its collector coupled to the downlamp 246'thoru gh a connector terminal 256 and its base terminalconnected to the cathode of, the SCR 242 through a directional diode 258in series with an input resistor-260. Qui te clearly, the SCR 242, whenrendered conductive, simultaneously provides drive current to the downrelay driver circuit 212 and the down lamp driver circuit 250 so as tocause energization of the directionalsolenoid 78 and illumina- Thebalememory circuit 180 includes a silicon controlled rectifier 266 and'agate terminal bias network consisting of resistors 268, 280. Holdingcurrent for the anode terminal of the SCR 266 'is normally-provided witha description of from the power supply '80 through the normally closed(lower) contacts of the pressure switch l60.via the drive-down connectorterminal 166 and the R-C' decoupling network 244. Current from thecathode of the SCR 26 6.is coupled through a directional diode 282 to aconnection 284 withthe cathode terminal of the pack memory SCR 184 fromwhichpointthe drive current for the motor, relay driver circuit 186 isderived. Finally, the gate terminal of the SCR 266 in the bale memorycircuit 180 receives its trigger signal in response to the occurrence ofa bale initiation pulse at the terminal 150, current being routed to thegate terminal of the SCR-266 through the R-C decoupling net work 266, adirection diode 290 and the bias resistor 268. l

A brief description of: the operation of the circuit described thusfarwill facilitate further analysis of the system as a whole. Beforeinitiation of either of the principal functions, the system is in aquiescent condition in which the pressure plate 30 is at its uppermostposition. I

The high limit switch 164 is openso that the dc. supply voltage is notpresent'at terminals 166, 170,174 in which case the pack'memory circuit182' and the bale memory circuit180 are inactive or non-conductive.

Manual operation of the function selector switch 140 I to thePACK-RETURN position causes a pack initiation pulse to be routed fromthe power supply 80 to the .pack connector terminal 152. Anode circuitfor the pack memory SCR 184 momentarily flows through the directionaldiode 19 8 from the R-C decoupling, network-188, while gate current forthe sameSCR 184 is provided through the diode 190 and resistor 192. TheSCR 184beginscon'ducting and, via its'cathode current, renders the motorrelay driver circuit 186 conduca 10 rent frorn'the pack terminal 152through the directional diode 236 and resistor 230. The SCR242 beginsconduction. The gate signal for the SCR 242 is also applied to thedownrelay driver circuit 212 through the resistor 231 so as -to initiateconduction in the transistor 214 to energize the directional-valvesolenoid 78 so that the pressure plate 30 begins movement in a downwarddirection. I I i As the pressure plate 30 leaves its'rest position, the

high limit switch 164 (FIG. 2a) closes to replace the pack initiationsignal as a source of drive current for the hold'terminal 170,-whichsupplies the anode of the pack memory SCR 184, and the drive downterminal 166 which supplies the anode current for the drive down memorySCR 242. I v

The pressure plate 30 continues its downward travel, with the drive-downmemory circuit 240 hold the down lamp driver circuit 250 and the downrelay driver circuit 212 in conduction.

Initiation of'the BALE function by movement of the mode selector switchto the BALE position produces a similar result, since both the baleandpack functions have a common start. The bale initiation pulse at theterminal activates the balememory circuit .180 'by simultaneouslyproviding a signal to the gate of the SCR 266 (through the R-C network226, the

diode 290 and resistor 268) and to-the anodethereof down memory SCR'242is connected to the anode of the bale memory SCR 266 and is suppliedsimultaneously therewith-while the gate voltage for the SCR 242issupplied from the bale terminal 150 through-the R-C network 226, thediode 228 and resistor 230. Con- I f duction through the down relaydriver circuit 212 is ini-' tiated by the bale initiate pulse appearingat the gate of the drive down memory SCR 242,--and conduction inboth'the down relay. driver circuit 2l 2and the down lar np'drivercircuit 250 is sustained by "conduction through the drive-down memorySCR 242.

In additionto the down direction lamp 246, there provided an updirection lamp 300 for indicating to the operator the condition ofupward travel of the pressure plate 30. The lamp'300 is controlledby anup lamp driver. circuit 302 consisting of a transistor 304 of the NPNtype having its emitter coupled to ground through i a resistor 306 andits collector connected to the control terminal of the lamp300throughthe up lamp drive connector terminal 308. Conduction through thetransistor 304, and hence illumination of the up lamp 300,

is normally controlled by the conduction state of the pack memory SCR184 asa result of theconnection of i the cathode of the SCR 184 to thebase of the transistor 304 through a pair' of input resistors 310, 3 12.However, it isdesirable to inhibit operation'of the up lamp drivertransistor 304 and the lamp 300 when the pack memory SCR 184 is inconduction if the pressure plate 30 is moving in the down direction. Tothis end, there is provided a second transistor 314 of the NPN typewhich is shunted across the base-emitter circuit of the transistor 304;and controlled from the cathode of the drive memory SCR 242 via a baseresistor3l6. The emitter of the up lamp driver inhibit transistor 314 isreferenced to ground through an emitter resistor 318.

-Whenever the drive down memory SCR 242 is conducting, the inhibitingtransistor 314 is similarly con as a result of initiation of thisfunction. Upward movement of the pressure plate 30 does notautomatically occur asa result of initiation of the baling function.Therefore, itis necessary for the operator to manually engage. the modeselector switch l40.and turn it to the PACK-RETURN position at the endof the baling function in order to begin the upward movement of thepressure plate 30.

Returning to the operational description of the packing function, thepressure plate 30 travels down through the chamber 12 and compresses thecontents thereof until the predetermined threshold pressure(approximately 2,000lbs. in an actual application) is reached. At thispoint the contact arm of thepressure switch 160 moves from'its normallyclosed position to an open position (upward in FIG. 2a which causessupply voltage to be removedfr'om the drive down terminal 166 andhencefrom the anode of the drive down memory SCR 242. Conduction in thedown relay driver circuit 212and the down lamp driver circuit 250 stops,causing deenergization of the directional valve solenoid 78 andextinguishing the down indicator light 246 on the operators panel 50.The up lamp driver circuit 302 immediately becomes conductive toilluminate the up direction lamp 300 as the inhibiting transistor 314 isrendered non-conductive along with the drive down memory SCR 242.

Deenergization of the directional valve solenoid. 78 allows thedirectional valve to return to its normal condition which causes thepressure plate 30 to be driven in the upward direction. Since the motorrelay driver Circuit 186, and the-motor drive solenoid 72 are heldclosed terminal so as to remove-the d.c. supply voltage from the drivedown connector terminal 166; During the downward operation of thepressure plate 30 in the BALE mode, the bale memory circuit 180, themotor relay driver 186, the drive-down memory 240, the down-relay drivercircuit 212, and the down lamp driver circuit 250 are conductive.However, removal-of the dc. supply voltage from the drive down connectorterminal l66 deactivates the bale memory circuit 180 by depriving theSCR 266 of its anode current and simultaneously deactivates thedrive-down memory circuit 240 by depriving the SCR 242 of its anodecurrent. Deactivation of the bale memory circuit 180 terminates thedrive current to the motor relay driver 186, while deactivation of thedrive-down memory circuit 240 terminates the input current to the downrelay driver circuit 212 rendering this circuit inoperative so as toleave the pressure plate 30 in its lower position to hold'the contentsof the chamber 12 at the threshold compres sion pressure. The door 16 tothe chamber l2 may then be opened to allow the operator to tie thecompressed bundle. y The function of the down lamp memory circuit 320 isto provide a visual signal to the operator of the position of thepressure plate when the bale cycle is completed. The bale cycleterminates when thecomin conduction by the conductive condition of. thepack memory SCR 184, the pressure plate 30 automatically reverts fromtravel in the downward direction to travel in the upward directiontoward a-position of full retraction from the contents of the chamber12.21130, since the pack memory SCR 184 remains in conduction, the uplamp driver circuit 302 remains in conduction to give a vis ualindication to the operator of the direction of movement of the pressureplate 30.

The pressure plate 30 movesupward through the chamber 12 to theretracted position at which point it comes in contact with the actuatorfor the high limit switch 164, opening the switch 164 and disconnectingthe dc. power supply from the hold terminal 170, and hence depriving thepack memory SCR 184 of its anode current'As the pack memory SCR 184ceases conduction, drive current for the motorrelay driver ,186disappears and the pump motor drive solenoid 72 is de energized. Thepump stops and the machine re mains in a quiet condition until a furtheroperation is initiated. Also, as the pack memory SCR 184 ceasesconduction, drive current for the up lamp driver traneventuallyencounters resistance equal to the threshold pressure of the switch 160,causing the contact arm of the switch 160 to move upward from itsnormally mum compression pressure-of the pressure plate 30. When themachine is in this .state,'the d.c.supplyvo1tage to the pressure holddown terminal 166 is removed by the opening of the compression pressureswitch 160. Thus, the drive down memory SCR 242 is deprived of anodevoltage and ceases conduction. At this point, the down lamp drivertransistor 252 would also cease to conduct and the'down lamp 246 wouldbe extinguished if an alternate source ofdrive for the down lamp. drivertransistor 252j'was not provided. It is the function of the 1 down lampmemory circuit 320 toprovide this alternate drive source, therebyenabling the operator to re ceive a visual output of the position of thepressure plate 30 while the cycle and idle. I g

Specifically,; the down lamp memory circuit 320 is principally composedof a SCR 322 having its anode terminal supplied by the off terminal143through an R-C decoupling network 324 and its cathode terminalconnected to 'the'base of the down lamp driving transistor 252 through aresistor 326. The cathode terminal of the SCR 322 is also referenced toground through a resistor 328. The gate terminal of the SCR 322 receivesits trigger signal from the'bale initiationterminal 150 through'an 'R-Cdecoupling network 226, a blockingdiode 328 and a bias-resistor 330. Anadditional bias resistor 332 connects the gate and cathode terminals.Thus, the SCR 322 begins conduction whenever its gate terminal receivesa bale initiation signal from the manual mode selector switch throughthebale initiation terminal and ceases conduction only when its anodeterminal current is interrupted by turning the manual mode selectorswitch 140 to the PACK- RETURN position. f g

It will be recalled from the prior description that the contacts 141,142 of the manual mode selector switch 140 are normally closed in theOFF and BALE positions and normally open in the PACK-RETURN'position.Thus, the SCR 322 of the down lamp memory circuit 320 and the down lampdriving transistor 252 are machine 'is' the completed bale r 13 inconduction and the downlamp 246 remains illuminated after maximumcompression-pressure of the pressure plate 30 is achieved. Only whenthe. operator subsequently generates a pack initiate signal by turningthe manual mode selector switch 140 to the PACK- RETURN position arethese circuits 320, 250 deenergized and the down lamp 246 extinguished.s

The functioning ofthe return logic circuitry 450 will be discussedbelow. Suffice it to say at this time that the operator has thecapability, after the'compressed material has been bound andthecompaction chamber doors 16, 28 have been closed thereby activatingthemagnetically actuated switch 130, to cause retraction of the pressureplate 30 to its uppermost position by turning the manual mode selectorswitch 140 to the PACK- RETURN position. The compaction chamber door 16may then be reopened'to allow removal of the compressed bundle. i

Note that the magnetically actuated switch 130 re quires that bothcompaction chamber doors 716, 28 be closed before any movement of thepressure plate 30 can be initiated or sustained. That is, if themagnetically actuated'switch 130 is-open, the manual mode sele'ctorswitch 140 is disabled from sending any pressure plate 30initiating'signa'ls to the bale initiate terminal 150 or the packinitiate terminal 152. Also, if the pres: sure plate 30 is in motion,opening of either of the compaction chamber door 16,28 also opens themagnetically actuated switch 130, thereby depriving the hold terminall70 ,'the pressure plate drive down terminal 166, the pack memoryci'rcuit'l 82, the bale memory circuit 180 and the motor relay drivecircuit 186 of supply voltage. Thus an'y movement of'the'pressure plate30 immediately ceases upon'opening of either compac-, tion chamber door16,28. Therefore, it is possible for the operator to remove thecompressed bundle without any interference from or injury caused bymovement of thepressure plate 30. A

' Turning now to the, tamping function, it'will be reealled that thisfunction occurs whenever the volume of the compaction chamber 12approaches a predetermined full level. This function generates a secondcompaction' cycle if the firstcompaction cycle fails to corn 1 1 1'4 SCR342. The sea 342 begins conduction when a positivepulse at the full"condition terminal 174 is conducted through the RC decoupling network350, the

directional diode 344 and the biasresistor 346 to the gate terminal ofthe SCR 342. The full condition pulse is generated atlthe full conditionterminal 174 whenever the pressure plate 30 moves from its uppermostrest position, thereby closing the" normally open contacts of the highlimit switch 164, and reaches the threshold compression pressure of thepressure switch 160 before the'pressure plate 30 advances to thepredetermined full level of the compaction chamber 12-. The low limitswitch 172, which is normally closed, is mechanically actuated to anopen condition whenever the pressure plate 30 advances to a positionbelow the'predetermined full level. i

The details of mechanical actuators for level sensing switches, such asthe low limit switch 172, arewithin the knowledge of those skilled inthe art and need .not be set forth here. Thus,- anytime that the machinecom pacts its contents to the point where the pressure. plate 30 isabove the full level .when the maximum compaction pressure is achieved,a full'condition pulse is generated at the full condition terminal 174.When the full condition pulse is applied to the gate terminal of .thefull memory SCR 342, the SCR 342beg'ins conduction and suppliesoperating voltage to the tamp pulse generator circuit'360. I v

The tamp pulse generator circuit 360 is principally composed of aprogrammable unijunction transistor press the volume of the compactionchamber 12 belo the full level. lf the second compaction cyclecompresses the volume below the full level, additional ma- ,terial maybe inserted. However, if the volume remains above the full level afterthe second compaction cycle, the operatoris visually signaled that thecompaction chamber 12 is full, indicating that the contents of thechamber 12 should be removed before attempting further compacting.Specifically, the full memory circuit 340, the tamp pulse generator 360,the tampmemory 380, the full lamp memory .400, the full lamp flashercircuit410 and the full lamp driver circuit 430 accomplish thesefunctions in the mannerhereinafter de-" scribed;v r

The full memory circuit 340 is principally composed of an SCR 342 havingits'anode terminal supplied by the dc. supply line at the terminal 148through the'R-C decouplingv network 324-and its cathode terminal .con-

'ne'cted to the bias resistors 364, 366, 3700f the tamp (PUT) 362 havingits gate terminal connected .to-the voltage reference resistors 370,372, with-the'resistor 370 connected to the 'cathode'terminal of the SCR342- and-the resistor 3752 reference to ground. The anode of the PUT 362is-connected to the timing resistor366- and the timing capacitor 368,with the timing resistor 366 also connected to the cathode terminal ofthe SCR 342 and the timing capacitor'368 reference to ground. The loadresistor 364 provides a sufficient load to the full memory SCR 342 toensure'that-the SCR 342 remains in conduction and is connected between'the cathode terminal of the SCR 342 and ground. The

cathode terminal of the PUT 362 is referenced to ground through theresistor 374 and is connected to the tamp-memory SCR 382 through thegate terminal biasing resistors 376, '384.

The function ofthe tamp pulse generator circuit 360 is to provide apulse to the tamp memory circuit 380 which'is delayed in time withrespect to-the initiation.

of conduction in the full memory SCR 342. When the SCR 342 beginsconduction, a voltage reference is im-' mediately established on thegate terminal of the PUT 362 by the voltage reference resistors 37.0,372. The voltage of the timing capacitor 368 begins to rise as it ischarged through" the timing resistor 366. When the voltage on the timingcapacitor 368, and hence that on the anode terminal of the PUT 362,reaches thev voltage reference at the gate terminal of the PUT 362,, thePUT 362 istriggered into conduction and'the charge on the timingcapacitor is discharged through the PUT cathode terminal to generate apositive pulse to the gate biasing resistors 376, 384 of the tampmemory'SCR 382.

The delay time of thepulse is directlyproportional to the-value of thetiming resistor 366 and the tiniing capacitor 368, the, values beingselected to produce a delay time of a few seconds, e.g.-, 5 seconds.

The tamp memorycircuit 380 is principally composed of an SCR 382 havingits anode connected to the dc. supply through the off terminal 148 andthe R-C decoupling network 324 and its gate terminal connected to thebiasing resistors 376, 384. The cathode terminal of the tamp memorySCR382 is referenced to ground through the resistor 386 and is alsoconnected to the anode of the full lamp memory SCR 402 and to thedifferentiating capacitor 388. The other terminal of the differentiatingcapacitor 7 388 is referenced to ground through the resistor 390 andis.connected to the gate of the drive down memory SCR 242 through thedirectional diode 392 and the resistor 394.

The function of the tamp memory circuit 380 is to provide d.c. supplyvoltage to the anode of the full lamp memory SCR 402 and to provide atrigger pulse tothe gate of the drive down memory SCR 242. When thecircuit 380.

The full'lamp memory circuit 400 is primarily coinposed of an SCR 402having its anode terminal connected to the cathode terminal of the tampmemory 'SCR 382 and its cathode terminal connected to the resistors 414,418, 422 of the full lamp flasher circuit 410. The gate terminal of theSCR 402 is connected to the full condition terminal 174 through the RCcoupling network 0, the directional diode 404 and the bias resistor 406.An additional bias resistor 408 com nects the gate and cathode terminalsof the SCR 402.

' The. function of the full lamp memory circuit 400 is to provide d.c.sup'ply voltage to the full lamp flasher the gate terminal of the fulllamp memory SCR402 through the R-C decoupling network 350, thedirectional diode 404 andthe bias resistor 406. Since the anode terminalof the SCR 402 had d.c. supply voltage applied by the conduction of thetamp memory SCR 382, the SCR 402 is nowtriggered into conduction. Notethat if the tamping function is successful in compressing the contentsof the compaction chamber 12 to a. point below the full level, a fullcondition pulse is not generated at the full conditionterminal 174 atthe end of the tamping cycle because the low limit switch 172 openswhenever the pressure plate 30 advances to a point below the full level.Thus, the full lamp memory SCR 402 is triggered into conduction only ifthe tamping operation isunsu'ccessful in compacting the material in thecompaction chamber 12 to a point below the full level.

The full lamp flasher circuit 410' consists primarily of a programmableunijunction transistor (PUT) 412 having its gate terminal connected. toa pair ofvoltage reference resistors 414, 416 and its anode is connectedto a timing resistor 418, a timing capacitor 420 and the full lampdriver'resistor 436. The timing resistor 418 is referenced to the dc.supply voltage provided by the full lamp memory SCR 402 and. the timingcapacitor 420 is referenced to ground. The loadresistor 421 ensures thatsufficient load is provided'to the full load memory SCR 402 to sustainits conduction. The cathode of the PUT 412 is connected to a dischargeresistor .422 which is referencedto ground. When the full lamp memorySCR 402 begins conductiomthe voltage reference resistors 414, 416immediately establish a voltage reference at the gate terminal of thePUT 412. The timing capacitor 420- begins to charge through-the timingresistor 418. when the timing capacitor voltage, and hence the voltageat the anode terminal of the PUT 412, reaches the voltage referenceestablished at the gate terminal of the PUT 412, the PUT 412 istriggered into conduction, dischargingthe timing capacitor 420 throughthe cathode terminal of the PUT 412 and they resistor 422. The chargingand discharging of the timing capacitor 420 continue as long as the fulllamp memory SCR 402 provides d.c. supply voltage. Thus, the output tothe full lamp'driver circuit 430 is a sawtooth waveform andthe fulllamp'flasher circuit 410 functions as a sawtooth oscillator. The periodof the sawtooth waveform is dependent upon vand directly, proportionalto the selected values of the timing resistor 418 and the timingcapacitor 420,- the values being selected to produce a waveform periodof less "than about'l second, e.g., about second.

The full lamp circuit consists primarily of a Darlington connection oftwo transistors 432, 434 of the NPN type with theircollector terminalsconnected to the full lamp 440 through thefull lamp terminals 438.,Theemitter terminal of the transistor 432 is connected to.

the base terminal of the transistor 434 and the emitter of thetransistor" 434 is referenced to ground through the resistor 442. Thebase terminal of the transistor 432 is connected to the timing capacitor420 and the anode terminal of the PUT 412 through the'resistor 436. Thesawtooth waveform'from the full lamp flasher circuit 410 alternatelydrives the full lamp driver transistor 432, 434 into and out ofconduction. The on-and off switching of the full lamp driver transistors432, 434 causes the full lamp 440 to flash, creating a more noticeableand visible warning indicator to the operator that the contents of thecompaction chamber 12 should be removed The full lamp 440 will continueto flash on and off until the anode terminal voltage of the tamp memorySCR 382 removed Specifically, flashing of the full lamp 440 may beextinguishedby' turningthe manual mode selector switch to the PACK-RETURN position which causes theoff terminal 148 to drop in voltage.

Directing attention now to thereturn function, this function is usefulfor returning thepressure plate 30 to its uppermost position after thebaling operation or after, any machine malfunction or other occurrenceleaves the pressure plate 30 in any position except its uppermostposition. One example of an occurrence which leaves the pressure plate30in a lowered position is the opening of either compactionchamber door16, 28 while the pressure plate 30 is in motion. This causes '17 themagnetically actuated switch 130 to open whereupon movement of thepressure plate 30 immediately ceases.

-It will be recalled that whenever the pressure plate 30 is not in itsuppermost position, the low limit switch 164 472 which is referenced toground, a pair of voltage reference resistors 468, 470 and thedirectional diode "466. The gate terminal of the PUT 474 is connected toa resistor 476 which is referenced to the dc. supply voltage at thecapacitor 464. The cathode terminal of I the PUT 474 is connected to thegate biasing resistors 478, 480 of the return memory SCR 482. Anadditional .SCR 482 gate to cathode terminal bias resistor 484 is used.The anode terminalof the SCR'482 is connected .tothe hold terminal 170throughthe line smoothing capacitor 492 and the directional diode454.The cathode terminal of the SCR 482 is referenced to ground through-theresistor 486and is connected-to the base terminal of the return currentdriving transistor 409 of the NPN type through the resistor 488. Theemitter ter.-

minal of the transistor 490 is connected to ground while its collectorterminal is connectedto the anode terminal of the bale memorySCR 266andthe anode terminal of the drivedown memory SCR 242. The return logicgeneration transistor 462 of the NPN type has its base terminalconnected to the pack initiate ter- I minal 152 through the directionaldiode 452 and the resistor 456 and is referenced totground through theresistor 458. Theemitter terminal of the transistor 462 is connected toground while its collector terminal is 18 I supported by thecapacitor'472, is at a higher potential than the gate terminal. The PUT474 is triggered into conduction and thecapacitor 472 iis dischargedthrough the cathode terminal of the PUT 474 and the resistor478. j j pThe discharging through the resistor 478 generates a positive pulse tothe gate terminal of the return memory SCR 482 through thegatebias'resistors480, 484. Since the anode terminal of the returnmemory SCR 482 is connected to the dc. supply voltage on the holdterminal 170 through the directional diode 454-, the

SCR 482 is triggered into conduction when the positive pulse is appliedtoits gate terminal. The conduction of SCR 482 drives the return drivingtransistor'490 into conduction by supplying base terminal currentthrough the bias resistor 488. The conduction of transistor 490 'pullsthe pressure plate drive down line, which is connected to the anodeterminals of the bale memory SCR 266 and the drive down memory SCRJ242,down to ground potential. The SCR 266 and the SCR 242 are ,now deprivedof anode voltage and any prior conductionceasesrThus, the return logiccircuit450 cancels any prior bale'memory 180 and cancels any prior drivedown memory 240. Thedirectional valve solenoid 72 is deenergized whenthe drive down memory 240 is cancelled and the directional valve 74returns to is normal position. Note that when the return logic-circuit450 was actuatedb'y a pulse on the pack initiate terminal Y152 and thed.c.', supply voltage on the holdterminal the hold terminal 170 on itsanode terminal. and the connected to the capacitor 464 and theresistors460,

The return circuit 450 functions to deenergize the bale memory circuit180 and the 'drive down memory circuit 240 inth anner hereinafterdescribed. The return circuit 450 receives d.c. supply voltage from thehold'terminal 170 through the directional diode 454. The capacitor'464rapidly charges toward the dc. supply voltage through the resistor 460.The capacitor 472 charges rapidly toward the voltage reference leveldetermined by the voltage reference resistors 468, 470. When theoperator wishes to return the pressure plate 30 toward its uppermostposition, the manual mode selector switch 140 is turned to thePACK-RETURN position. A pack initiate pulse is then generated at thepack initiate terminal .152 which is conducted to the base of the returnlogic transistor462through the R-C decoupling network 188, thedirectionaldiode 452 and the resistor 456. Thepack initiate signal atthe base terminal of the transistor, 462 causes the transistor 462 toconduct; thecollector terminal dropping in voltage to nearly groundpotential. The capacitor 464 israpidly discharged through the transistor462 and the gate terminal of the return pulse generator PUT 474 ispulled toward ground potential through the resistor 476. The

anode terminal of the PUT 474 momentarilystays at anode terminal of thePUT 474, which has its potential pack initiate pulse'from the packinitiate terminal 152 on its gate terminal. Thus, the motor drive relay172. is

energized by the packrnemory SCR 184 supplying d.c.' voltage to themotor relay driver circuit186. With the hydraulic solenoid74 in itsnormal position and the hydraulic motor 68 running, the pressure plate30 retracts toward its uppermost position. When the pressure plate 30reaches its uppermost position, or when refuse is lodged between thecompaction chamber topplate l1 and the pressure plate 30, the highlimitswit'ch 164 assumes itsnormally open position'causing the dc. sup.-

ply voltage on the hold terminal l'70'to drop. When refuse is solodgedin the space abovethe pressure plate 30, the plate 30' upon stoppingdoes not return to'its-uppermost position, but resumes its next downwardstroke from this starting position. Since bias and drive current for thereturn logic circuit 450 is supplied by the hold terminal 170, thereturn pulse generator PUT 474, the return memory SCR'482 and the returndriver transistor 490 are disabled. The directional diode 466 nowallowsrapid discharge of thecapacitor472 to prevent further PACK-RETURNcominandsfrom the operator from generating another return signal.

It will be understood from the above circuitdescription that if thecapacitor 472 was not fully discharged, another return pulse would begenerated by the Put 474 whenever the manual mode selector switch isturned to the PACK-RETURN or BALE positions thereby supplying voltage tothe hold terminal through the directional diodes 198, 292. This wouldresultin the undesirable system operation of inhibiting any downwardmovement of the pressure plate 30. The

directionaldiode 466 provides a rapid discharge path for thecapacitor472 and eliminates this problem. If the capacitor 472 isdischarged, no such hazard occurs when the manual mode selector switch140 initiates the PACK-RETURN or BALE functions as described above.

Turning now to the automatic shut-off function, this functiondeenergizes the drive motor after a predetermined short period of time,eg 45 seconds, beyond the initiation of any operation by the operator.This function prevents damage to the unit or injury to the opera-.

tor which might result from any system malfunction.

The automatic shut-off function is performed by'the end cycle timercircuit 500. The dc. supply voltage for the end timer circ'uit 500 isderived directly from the pressure plate drive down terminal 166. Theend cycle PUT 502 has its gate terminal connected to a pair of voltagereference resistors 508, 510 and its anode terminal connected to atiming resistor 504-referenced to the dc. supply voltage and a timingcapacitor 506 referenced to ground. The timing capacitor 506 chargesthrough the timing resistor 504 until the anode terminal potential ofthe PUT 502 reaches the potential of the gate terminal. The PUT 502 isthen triggered into conduction and the timing capacitor 506 isdischarged through the PUT 502 cathode terminal and the resistor 512which is referenced to ground. The delay time of the pulse which isgenerated at the resistor 512 is directly proportional to the selectedvalues of the timing resistor 504 and the timing capacitor 506, thevalues being selected toproduce a short' delay time, e.g. of about.45seconds. The delay pulse generated at the resistor 512 drives a pair oftransistors 514 and 516 of the NPN type and connected in the Darlingtonconfiguration. The base terminal of the transistor 514 is connected tothe discharge resistor 5112 and the PUT 502 cathode terminal and'theemitter terminal of the transistor 514 is connected to the base terminalof the transistor 516. The transistor 516 has its emitter connected toground. The collectors of both transistors 514, 516 are connecteddirectly to the pressure plate drive down terminal 166. v

' When the pressureplate 30 leaves its uppermost po- 20 H malfunctionisrepaired, the pressure plate can be retracted to its uppermost positionby using the previously described return function.

If the pressure plate 30 reaches maximum compression pressure within theexemplary 45 second delay of the end cycle timer circuit 500, thecircuit 500- is reset to begin another 45 second delay period when thepressure plate 30 beginsretracting toward its uppermost position. Theinterruption of the dc. supply voltage on the pressureplate drive downterminal 166 by the compression pressure switch 160 causes the gateterminal of the PUT 502 to drop in voltage along with the pressure platedrive down terminal. However, the voltage of the anode terminal of thePUT 502 is-supported by the timing capacitor 506. As the voltage of thegate terminal of the PUT 502 drops below that of the anode terminal, thePUT 502 is triggered into conduction and the timing capacitor 506 .isdischarged through the cathode terminal of the PUT 502, the dischargeresistor 512 and the drive down transistors 514, 516. Thus,.the endcycle timer circuit 500 is reset to begin another delay period todeenergize the motor drive relay in the event that some malfunctionprevents the pressure plate 30 from reaching its uppermost positionwithin45 seconds.

7 Note that the pressure plate 30 retraction is automatic when thesystem is in the compaction mode and must be manually. initiated bythemanual modeselector switch 140 when the system is in the bale mode.However, the delay period does not begin until the system is manuallyinitiated (assuming no leakage of hydraulic fluid and consequent loss offluid pressure due to-leaky seals and the like) when it is in the balemode because of the opening of the'compression pressure switch 160 whenmaximum compression pressure is achieved deprives the endcycle timercircuit500 of do. supply .voltage.

Similarly, when the system'is in the tamp mode, each achievement ofmaximum compress'ionpressure of the pressure plate 30 opens the pressureswitch 160 and interrupts the dc. supply voltage to theend cycle timercircuit 500. The circuit 500 is thereby reset to begin ansition, thehigh limit switch 172 closes and dc. supply within seconds, in thisexample, thereby opening the compression pressure switch 160, the PUT502 is triggered into conduction as previously described. The

-,delay pulse from the PUT 502 cathode terminal drives the end cycledriver transistors 514, 516 into conduction which causes the dc. supplyvoltage on the pressure plate drive down terminal 166 to drop. Since thehold terminal 170 is connected to the pressure plate drive down terminal166 through the compression pressure switch 160, the dc. voltage levelof the hold terminal 170 drops with that of the pressure plate drivedown terminal 166. The drop in voltage on both of these terminals causesthe anode terminals of the pack memory SCR 184 and the bale memory SCR266 to cease any prior conduction. Since the motor relay driver circuit186, which energizes the motor relay 72, receives its d.c.supplyvoltage-from either of the SCRs 184, 266, the motor relay circuit186 and the motor relay 72 are deenergized. Thus, the drive motor 68 isdeactivated and the pressure plate 30 ceases any motion. After the otherdelay period for each change in directionlof the pressure plate 30. Theend cycle timer circuit 500 has no effect .on norrna'lcompaction cyclessincenormal movementof the pressure plate.30 in any direction ceases,within the delay period.

The above discussion has described the five principal functions of thesystem:' the compact function, the bale function, the tamp function, thereturn function and the automatic shut-off function. The accessory relaydriver circuit 520 illustrates the capability of adding additionalcontrol functions to the system. This circuit 520 is presentedforillustrative purposes only and to indicate the versatility of thecontrol system in allowing additional user-desired functions to beimplemented.

Such user-desired functions may include,'.but are not limited to,automatic cycling devices to initiate compaction cycles at predeterminedtime intervals.

I claim as my invention:

1. A control system for a'compacting machine having a compaction chamberfor receiving material to be compacted, a pressure plate spanning thearea of said chamber for compressing the contents thereof, a reversibledrivesource for moving said pressure plate in the forward and reversedirections within said compaction chamber, sensing means associated withsaiddrive to retract the pressure plate and permit removal of thecompressed contents from the compaction chamber,

said control system-including means for initiating the forward operationof said drive source, emergency shut-off means including a) time delaymeans responsive to the initiation of said forward operation forproducing an output at a predetermined interval after said initiation offorward operation, and b) means responsive to said output for inhibitingfurther operation of said drive source, saidtime delay interval beingsufficiently long to enable normal forward or reverse operation of .saidpressure plate to be completed before said tion thereof by renderingsaid drive source inoperative wheneverthe pressure plate reaches saidfully retracted position, and said sensing means also being responsiveoutput is produced and sufficiently long to enable normal forward orreverse operation of said pressure plate to be completed before saidoutp0ut is produced and sufficiently short to allow said output to beproduced as soon as the period of operation of said drive source exceedsthetime normally required for full forward or reverse travel of saidpressure plate.

'2..A control system for a compacting machine having a compactionchamber for receiving material to be compacted, a pressure platespanningthe area of said chamber for compressing the contents thereof, areversible drive source for moving said pressure plate in the forwardand reverse directions within said compaction chamber, and a panel atthe top of the compaction chamber for enclosing said chamber, saidcontrol system including means for sensingthe fully retracted positionof said pressure plate to prevent'fu'rther retracto, theposition of thecompaction chamber panel to render said drive source inoperativewhenever material lodged between the pressure plate and the compactionchamber panel causes said panel to flex as the pressure plate retractsthereby preventing damage to said compaction chamber panel 'by theretracting pressure plate.

3. A control system according to claim 2 wherein the retraction positionsensing means comprise a slidably mounted rod projecting'throughthecompaction-chamber panel, said rod being engageable by the retractedpressure plate to slidably move upwardly and. thereby render said driveinoperative. I a

4. A control system for acompacting machine having a compaction chamberfor receiving material to be compacted, a'pressure plate spanning thearea of said chamber for compressing the contents thereof, a reversibledrive source for moving said pressure plate in the forward and reversedirections within said compaction chamber, a panel at the top of thecompaction chamber for enclosing said chamber, retraction positionsensing meanscomprising a slidably mounted rod projecting through thecompaction chamber panel, said rod being engageable by theretractedpressure plate to slidably move upwardlyand thereby render said driveinoperative, said retraction position sensing means further including asecond retraction position sensing means mounted on saidrod and inengagement with the compaction chamber panel so that material lodgedbetween the top of said pressure plate and said panel causes said panelto flex upwardly during retraction of saidpressure plate thereby causingupward movement of both the second retraction position sensing means andthe rod to render the drivesource inoperative and thereby inhibitfurther retraction of said pressure plate.

1. A control system for a compacting machine having a compaction chamberfor receiving material to be compacted, a pressure plate spanning thearea of said chamber for compressing the contents thereof, a reversibledrive source for moving said pressure plate in the forward and reversedirections within said compaction chamber, sensing means associated withsaid drive source for providing an output whenever the compressionpressure of the pressure plate against the chamber contents reaches apredetermined threshold value, means responsive to said output andoperative on said drive source to stop the forward advancement of saidpressure plate and to hold the contents of said chamber at saidpredetermined threshold compression pressure to facilitate baling of thecompressed contents, and means for reversing the operation of said drivesource to retract the pressure plate and permit removal of thecompressed contents from the compaction chamber, said control systemincluding means for initiating the forward operation of said drivesource, emergency shut-off means including a) time delay meansresponsive to the initiation of said forward operation for producing anoutput at a predetermined interval after said initiation of forwardoperation, and b) means responsive to said output for inhibiting furtheroperation of said drive source, said time delay interval beingsufficiently long to enable normal forward or reverse operation of saidpressure plate to be completed before said output is produced andsufficiently long to enable normal forward or reverse operation of saidpressure plate to be completed before said outp0ut is produced andsufficiently short to allow said output to be produced as soon as theperiod of operation of said drive source exceeds the time normallyrequired for full forward or reverse travel of said pressure plate.
 1. Acontrol system for a compacting machine having a compaction chamber forreceiving material to be compacted, a pressure plate spanning the areaof said chamber for compressing the contents thereof, a reversible drivesource for moving said pressure plate in the forward and reversedirections within said compaction chamber, sensing means associated withsaid drive source for providing an output whenever the compressionpressure of the pressure plate against the chamber contents reaches apredetermined threshold value, means responsive to said output andoperative on said drive source to stop the forward advancement of saidpressure plate and to hold the contents of said chamber at saidpredetermined threshold compression pressure to facilitate baling of thecompressed contents, and means for reversing the operation of said drivesource to retract the pressure plate and permit removal of thecompressed contents from the compaction chamber, said control systemincluding means for initiating the forward operation of said drivesource, emergency shut-off means including a) time delay meansresponsive to the initiation of said forward operation for producing anoutput at a predetermined interval after said initiation of forwardoperation, and b) means responsive to said output for inhibiting furtheroperation of said drive source, said time delay interval beingsufficiently long to enable normal forward or reverse operation of saidpressure plate to be completed before said output is produced andsufficiently long to enable normal forward or reverse operation of saidpressure plate to be completed before said outp0ut is produced andsufficiently short to allow said output to be produced as soon as theperiod of operation of said drive source exceeds the time normallyrequired for full forward or reverse travel of said pressure plate.
 3. Acontrol system according to claim 2 wherein the retraction positionsensing means comprise a slidably mounted rod projecting through thecompaction chamber panel, said rod being engageable by the retractedpressure plate to slidably move upwardly and thereby render said driveinoperative.
 4. A control system for a compacting machine having acompaction chamber for receiving material to be compacted, a pressureplate spanning the area of said chamber for compressing the contentsthereof, a reversible drive source for moving said pressure plate in theforward and reverse directions within said compaction chamber, a panelat the top of the compaction chamber for enclosing said chamber,retraction position sensing means comprising a slidably mounted rodprojecting through the compaction chamber panel, said rod beingengageable by the retracted pressure plate to slidably move upwardly andthereby render said drive inoperative, said retraction position sensingmeans further including a second retraction position sensing meansmounted on said rod and in engagement with the compaction chamber panelso that material lodged between the top of said pressure plate and saidpanel causes said panel to flex upwardly during retraction of saidpressure plate thereby causing upward movement of both the secondretraction position sensing means and the rod to render the drive sourceinoperative and thereby inhibit further retraction of said pressureplate.